When the wind shifted on the afternoon of Apr. 22, 1915, on fields near Ypres, France, the Imperial German Army ushered in a dangerous new era in warfare. World War I (1914-1918) had become a standoff of opposing infantries fighting from trenches. To break the stalemate, the German Supreme Command made a decision to change strategy. At 5 p.m. German combat engineers opened 5730 cylinders of compressed chlorine gas. Blown by the wind, this yellowish-green cloud wafted across the battlefield toward the unprepared Allied lines. Surrounded and choking from the unexplained gas, French and Belgian troops in the trenches turned and ran for their lives. Unopposed, but wary of the ominous cloud, the German infantry advanced a few hundred meters toward Allied lines and then dug in for the night.
Airborne hazards, whether by warfare, terrorism, industry or nature occurrences represent an ever-present threat to military and civilian personnel. Airborne hazards can be roughly divided into three main categories: nuclear, biological and chemical. A large nuclear explosion (half a megaton, or more) injects most of its fallout particles and gases into the stratosphere, above the tops of clouds and above the altitudes at which removal of contaminants from the atmosphere by scavenging takes place. Very small particles in the stratosphere do not reach the ground before they are blown at least several thousand miles. Most of these tiny particles remain airborne for weeks to years, are very widely dispersed, and are blown around the world several to many times before being deposited. By then the radioactivity of iodine-131 (that has a half life of only a little more than 8 days) is so greatly reduced that it is not nearly as dangerous as is radioactive iodine deposited much sooner with the fallout from smaller weapons of several hundred kilotons, or less, explosive power.
Nuclear explosions smaller than about half a megaton (500 kilotons) inject all or most of their fallout to lower altitudes--within the troposphere, below the stratosphere. Most of such fallout is deposited during the radioactive cloud's first world-circling trip, when even quite rapidly decaying radioiodine still is dangerously radioactive. This greater danger from smaller nuclear weapons has been proved by numerous measurements of fallout from many nuclear test explosions, both foreign and American.
The cloud from the steam explosion that blew off the roof and otherwise damaged the Chernobyl reactor building, may have risen quite soon to 20,000 feet or more and was partially blown eastward clear across Asia and the Pacific Ocean. However, the top of the radioactive smoke cloud over the Chernobyl power plant, that burned for days, rose only about 3,000 feet above the ground. As a result, much of the airborne Chernobyl radiation stayed at relatively low altitudes where scavenging (removal) of smoke and fallout particles and gasses is most effective and rapid, due to aggregation on cloud droplets, rain-out, and dry deposition. In contrast, almost all of the fallout particles and radioactive gasses from a nuclear explosion are injected much higher, to altitudes where scavenging is less effective; there, the generally prevailing west-to-east winds promptly start transporting very small particles and radioactive gasses (that originate in the mid-latitudes of the northern hemisphere) around the world.
Variable winds for days carried much of the Chernobyl radioactive material northward to Scandinavian countries, then westward and southward to other European countries. The resultant wide dispersal of this fallout allowed time for both scavenging and radioactive decay before a small fraction of these invisible radioactive clouds rose and also were blown eastward by the prevailing high-altitude winds. These west winds carried an extremely small fraction of the radioactive emissions from the burning Chernobyl plant clear across Asia and the Pacific to America.
Accordingly, it can be clearly understood that early and precise tracking of radioactive fallout is critical. Before significant radioactive decay occurs and while the particles are particularly lethal, it would advantageous to track the early dispersion pattern at lower altitudes as fallout at that level would be more prone to make contact with populations. However, low-level winds are often difficult to track by satellite and numerous ground-based detectors are required to predict time-to-intercept and location data for such fallout.
Chemical weapons (herein "CW") release toxic gases or liquids that attack the body's nerves, blood, skin or lungs. They may produce surface effects such as tears, blistering, or vomiting, or cause hallucinations or loss of nervous control. Chemical attacks can contaminate an area for between several hours and several days, compromising equipment and forcing troops to wear highly restrictive protective clothing or take chemical antidotes whose side effects remain largely unknown. Chemical attacks cause widespread panic amongst both military and civilian populations, and their terror effects on civilians are potent. The large number of potential casualties places burdens on medical facilities and can overwhelm stretched military resources.
CW agents are frequently called war gases and a war where CW agents are used is usually called a gas war. These incorrect terms are a result of history. During the First World War use was made of chlorine and phosgene which are gases at room temperature and normal atmospheric pressure. The CW agents used today are only exceptionally gases. Normally they are liquids or solids. However, a certain amount of the substance is always in volatile form (the amount depending on how rapidly the substance evaporates) and the gas concentration may become poisonous. Both solid substances and liquids can also be dispersed in the air in atomized form, so-called aerosols. An aerosol can penetrate the body through the respiratory organs in the same way as a gas.
Chemical weapons depend more than any other armament upon atmospheric and topographical factors, whilst temperature, weather and terrain are important factors in determining the persistence of a given chemical agent. Large quantities of agents are required to achieve high lethality, and most chemical agents degrade rapidly, allowing areas, buildings and equipment affected to be reused (even if they require decontamination first). An attacker's use of persistent agents may mean that areas an attacker wishes to move across or occupy remain contaminated, necessitating the use of protective equipment or decontamination for attacking forces.
Chemical weapons can be delivered by a wide range of weapons systems, including ballistic and cruise missiles, combat aircraft-delivered bombs, artillery shells and land mines. According to the U.S. General Accounting Office, during the Iran-Iraq war, Iraq delivered mustard gas and tabun with artillery shells, aerial bombs, missiles, rockets, grenades, and bursting smoke munitions. The Soviet-made Scud-B and FROG-7 can deliver warheads bulk-filled with chemical agent and Iraq developed, deployed, but did not use, chemical warheads on its modified Scud missiles during the Gulf War. North Korea is also believed to have developed chemical warheads for its Scud B and Scud C ballistic missiles.
The most lethal chemical warfare agents are nerve agents, such as sarin, tabun, and VX, which produce convulsions and death by blocking an enzyme (acetylcholinesterase) needed to transmit messages in the nervous system. Nerve agents can be lethal in minute amounts: A tiny drop of VX on the skin, for example, can overcome an adult human in a matter of minutes.
Technologically, chemical and biological weapons are almost entirely different. Chemical weapons are highly toxic, manufactured substances that can be disseminated as vapors, aerosols, or liquids. Biological weapons, on the other hand, are living, disease-causing microorganisms or toxins (deadly chemicals derived from living organisms) which, in their most effective form, are disseminated as aerosols that are inhaled.
Biological weapons (excluding toxins, which resemble chemical weapons) consist of living, infectious microorganisms that are disseminated as aerosols through the atmosphere. Inhaled into the lungs, biological agents begin to multiply within the body, causing a disease that can incapacitate or kill the victim. Biological warfare aerosols are generally invisible, odorless, and tasteless. The onset of symptoms is usually delayed, often for as much as three to five days, so the victim of biological warfare may not even know that an attack has occurred until the disease has reached an advanced stage.
The worst outbreak of anthrax occurred in 1979, when a biological weapons plant in Sverdlovsk, Russia (present-day Yekaterinburg), accidentally released airborne anthrax spores, killing 66 people. In 1998 American scientists at Los Alamos National Laboratory used newly developed techniques to determine that the spores released in the accident contained at least four different strains of anthrax. This raised concerns that Russia, and possibly other countries, may be working on a vaccine-resistant form of anthrax for use as a biological weapon. The United States government had previously planned to vaccinate all American personnel against anthrax; however, the possibility of genetically engineered new forms of the disease currently has scientists divided as to the effectiveness of such a vaccine.
Airborne threats are not limited to warfare or terrorism. Industrial accidents releasing toxins into the atmosphere require advanced detection and precise tracking to provide emergency response services. Natural disasters such as volcanic eruptions and forest fires produce airborne hazards wherein altitude level-tracking is desirable. In effect, the detection and tracking airborne substances may simply be a prelude to an additional ground-based threat as is the case in large-scale forest fires.
Thus, nuclear, chemical, biological and naturally occurring airborne dangers may threaten military and civilian populations. In those circumstances, it is important to provide early detection and warning services for medical, rescue and countermeasure operations. However, current satellite and ground-based methods are woefully ineffective in tracking low-altitude airborne hazards. Sudden wind shifts, topography and other factors greatly effect the direction and dissemination of airborne particles. What is needed is a new method and apparatus for tracking such hazards.
A method anticipated in the current invention utilizes the inherent advantages of balloons. Such advantages include low cost, minimal mechanical complexity, and more particularly, the fact that a balloon's direction of travel is substantially the same as that of the hazardous airborne substances. Accordingly, if an unmanned balloon is launched into a field of hazardous airborne substances, the balloon's position will substantially match that of the hazardous airborne substances.
It is notoriously well known that balloons have been used to transmit environmental data. For decades, weather balloons have been used in the measurement and evaluation of mostly upper atmospheric conditions. Information may be obtained during the vertical ascent of the balloon through the atmosphere or during its motions once it has reached a predetermined maximum altitude. Weather balloons are most often inflated with helium which is less dense than air. Atmospheric pressure, temperature and humidity information may be sent by radio from a balloon.
However, in view of the prior art in at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.